Buck DC-DC converter ICs, with internal MOSFET and freewheeling diode ???

Discussion in 'The Projects Forum' started by esm., Mar 11, 2012.

  1. esm.

    Thread Starter Member

    Jan 20, 2012
    30
    0
    Hi.
    I am looking for a buck converter IC available in a small SMD package like SOT-23 (or other small one) to a power supply with these parameters:

    Vin = 16 to 30VDC
    Vout = 4.4VDC
    Iout = 250mA

    The maximum output peak current is also 250mA. The 4,4V rail will be used to supply voltage to a constant current supply (to a Li-Ion battery charge management IC). If possible, a higher output current capability would be better, but 250mA is enough for me.

    It would be much better a buck converter IC who meet the parameters above and doesn't require the use an external MOSFET and also not require an external freewheeling diode. I didn't found.

    I'm using TPS63000 from Texas Instruments in some designs. It is a buck-boost converter that doesn't need an external MOSFET nor an external freewheeling diode when operates in buck mode.

    I have many 1A SMD inductors with values from 4.7uH to 68uH. I just need to define which IC to be used. If don't find an IC who meet the parameters above, I will need to use a LM2596-ADJ buck converter from National Semiconductors to do the buck conversion, but it requires much more PCB space than the IC I am looking for.

    Somebody know some good ICs to meet the parameters above?
    Preferentially, ICs that doesn't require external MOSFET, freewheeling diode and is availabe in a small SMD package like SOT-23.

    Or some other suggestions of ICs with bigger size package that doesn't require external MOSFET nor a freewheeling diode ????
     
  2. DickCappels

    Moderator

    Aug 21, 2008
    2,647
    631
    The MC34063 can be used that way. It is available in an SOIC 8 package. It is bipolar and the output is a Darlington pair, so there is some unavoidable loss there, but it should not have any problem with your current at the 16:4 voltage ratio. I would need an external free wheeling diode when used in a buck configuration, but it would be a small diode.
     
  3. John P

    AAC Fanatic!

    Oct 14, 2008
    1,632
    224
    The MAX1837 matches your criteria except that it needs an external diode.

    Have you tried Linear Technology?
     
  4. shortbus

    AAC Fanatic!

    Sep 30, 2009
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